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where underlying voids are suspected beneath the pavements and electrical room slab. A video
evaluation of the storm pipes in this area was also performed under the direction of Engineered
Solutions of Georgia on
November 4, 2016
. We understand that this evaluation determined that
there is a separation of the storm pipe that drains into the underground detention vault beneath
the pavements in parking deck P1, which allows subsurface water flows into the backfill soils in
this area. The original Grading & Drainage Plan dated April 28, 2009 and prepared by Kimley-
Horn and Associates, Inc. was also reviewed to determine the depth of new fill materials
proposed beneath the northeast portion of the building. This review indicates that approximately
12 vertical feet of new fill was placed beneath the east side of the building, where the ground
surface is approximately 7 feet below the lower parking deck. Significantly deeper new fill
depths are present below the parking deck level, where up to 19 vertical feet of new fill is shown.
Up to 28 feet of fill is indicated in the vicinity of the front loading dock area and an estimated 16
feet of new fill is shown in the area of the eastern stormwater drop inlet within the driveway to
parking level P1.
FIELD EXPLORATION
A total of eight (8) boring locations were explored within or adjacent to the areas of observed
distress. Based on our initial site visit, significant below grade utilities are present in the areas of the
proposed exploration and a private utility contractor, RHD Services, Inc. was contracted to identify
the location of underground utilities prior to selecting the specific boring locations. The initial
borings were drilled on November 4, 2016. The borings were performed using hand auger
techniques, which were proposed to be terminated at depths of 7 to 15 feet below the existing grades.
Four of the borings were performed through 4 inch diameter cores through the existing pavements
and the floor slab in the Main Electrical Room at the northeast corner of parking deck P1. These
specific boring locations included the Main Electrical Room at the northeast corner of parking deck
P1, The west side of the parking Deck P1 entrance where cracking is evident, near the eastern
stormwater drop inlet within the entrance drive to parking deck P1 and the sidewalk area near the
west side of the loading dock driveway. The remaining boring locations included the east side of the
building at the north corner, near the base of the adjacent retaining wall north of this corner, the
landscape area adjacent to the entrance to parking deck P1 and near the base of the exterior steps east
of the loading dock driveway. The approximate boring locations are shown on the Boring Location
Plans, Figures 1 & 2, attached with this report. The borings were located by our field engineer, who
supervised the drilling operations and maintained logs of boring. The boring logs will indicate the
depth, classification, relative density or consistency of the soils encountered, depth to rock or
groundwater and any unusual subsurface conditions noted.
Due to significant rock fragments within the existing fill soil encountered, each of the hand auger
borings encountered shallow refusal prior to penetrating the existing fill embankments. Numerous
boring offsets were performed for the borings not located in the concrete areas that were cored. The
hand auger boring depths ranged from 1 to 5 feet below existing grades. Dynamic Cone
Penetrometer Tests were performed in each boring where obvious rock fragments were not
encountered, to determine the relative densities of the soils encountered. It should be noted that the
only boring which encountered a void beneath the existing pavements was located in the main
electrical room, where a 4 inch thick void was present. The concrete thickness at the boring
locations ranged from 4.8 inches in boring B-3 in the electrical room slab, to approximately 6 inches
in boring B-7 in the sidewalk adjacent to the loading dock.